Actuating mechanism for tuning condensers



Nov. 17, 1959 A. NOYES, JR

ACTUATING MECHANISM FOR TUNING CQNDENSERS Filed Feb. 8, 1956 United States Patent O ACTUATING MECHANISM FOR TUNING CONDENSERS Atherton Noyes, Jr., Mountain Lakes, N.J., assignor, by mesne assignments, to Aircraft Radio Corporation, Township of Boonton, Morris County, N.J., a corporation of New Jersey (1958) Application February 8, 1956, Serial No. 564,171 4 Claims. (Cl. 74-10) This invention relates to actuating mechanism for tuning condensers and is directed particularly to providing means to provide for accurate control of a condenser from a remote point.

In airplanes, it is customary to control tuning condensers through flexible shafts such as are used for tachometers. In order to provide for accurate setting of the condenser notwithstanding wind-up effects in flexible shafts, it is customary to connect the flexible shaft with an actuating shaft which is connected to the movableplate shaft of the condenser through reducing gearing often having a gear ratio as great as 60:1. While this provides for accurate moving of the condenser shaft, it has been found unsatisfactory in that it makes it difficult for the operator to feel the limiting positions of the condenser shaft. A condenser shaft is ordinarily free to move through an angle of 180 and has its motion in each direction limited by a stop. In ordinary tuning where the operator turns the condenser shaft directly, he can easily feel the engagement of these stops which indicate to him the high and low frequency ends of the tuning range. When, however, the operator actuates the condenser through a flexible shaft connected through the condenser shaft through high-ratio speed-reducing gearing, his manual turning of the actuating shaft applies such great force to the condenser shaft that it is diflicult to feel the engagement of the stops on this shaft and there is considerable danger of breaking or injuring the stops by the large force applied.

My invention provides a means for overcoming this difliculty and thus enabling a remote operator both to set a condenser shaft accurately and also to feel the high and low frequency positions of this shaft to enable him to adjust his remote dial to agree with the actual position of the condenser plates.

In accordance with my invention, the turning of the condenser shaft is limited by a stop mechanism on the actuating shaft whose operation is controlled by a cam on the condenser shaft. In this way, the stop mechanism is not subject to injury by high torque and its engagement is easily felt by an operator who is tuning the condenser through a flexible shaft.

In order that the invention may be clearly understood, I will describe the embodiment shown in the accompanying drawings in which Fig. 1 is a partial plan view of a tuning condenser showing actuating mechanism embodying the invention;

Fig. 2 is a transverse section on the line 22 of Fig. 1, while Fig. 3 is a transverse section on the line 33 of Fig. 1 looking in the opposite direction;

Fig. 4 is a fragmentary longitudinal section on the line 4-4 of Fig. 2; and

Figs. 5, 6 and 7 are fragmentary sections taken on the line 5 of Fig. 2 and showing different positions of the parts.

The condenser, a part of which is illustrated in the drawings, has fixed plates 10 and movable plates 11 mounted on a shaft 12 journalled in a frame 13. An

actuating shaft 15 is connected to the condenser shaft 12 by reducing gearing, including a worm 16 on the actuat ing shaft and a gear 17 on the condenser shaft.

The reducing gearing is arranged to. avoid lost motion. End shake of the actuating shaft 15 and the worm 16 is prevented by providing the shaft with two thrust bearings 18, 19 which are urged apart by a spring 20. The bearing 18 is secured against the frame 13, while the bearing 19 is urged inwardly by the spring 20 which is mounted on a screw stud 21 on the frame 13. To avoid lost motion between the worm and the gear 17, the gear 17 is split into two parts, each of which is provided with teeth engaging the worm 16. One part 22 is fixed on the condenser shaft 12, while the other part 23 is loosely mounted on the shaft and connected to the part 22 by springs 24 which tend to cause relative rotation of the two parts. This results in holding the teeth of one part in engagement with one side of the worm thread, while the teeth of the other part are pressed against the other side of the worm thread.

A flexible shaft for remote control may be connected directly to the actuator shaft 15 or may be connected to it through bevel gearing 25 as shown.

The mechanism for limiting the turning of the condenser shaft 12 includes a cam 30 on the condenser shaft engaged by a movable cam follower 40 which controls the operation of a stop mechanism 50 which includes a pin 51 on the actuator shaft 15 and a blocking element 52 connected to the cam follower 40.

The cam 30 consists of two pieces 31, 32 adjustably bolted 'to a drum 33 on the shaft 12. Each of the pieces 31, 32 has an arcuate surface 34 of slightly less than The piece 31 has an inwardly inclined surface 35 at one end of its arcuate surface, while the piece 32 has an inclined surface 36 at the other end of its arcuate surface. The elfective positions of the two inclined surfaces may be adjusted independently by loosening the screws 37 which pass through arcuate slots 38 in the pieces 31 and 32.

The cam follower 40 is mounted on a lever 41 fulcrumed at one of its ends on a stud 42 on the frame 13. On the lower end of the lever is formed the blocking element 52 containing a recess 53 in which projects a stop 54 which lies in the path of the pin 51 on the actuating shaft when the lever 41 is tipped inwardly as shown in Figs. 2 and 3. The lever 41 is urged inwardly by a spring 43 which holds the cam follower 40 against the cam 30.

When the circular portion of the cam 30 engages the cam follower, the lever is pushed into an erect position in which the blocking member 52 at its lower end stands clear of the path of the pin 51 as shown in Fig. 7.

-When the cam 30 is turned so that the follower 40 engages either of the inclined surfaces 35 or 36, the lever is swung inwardly by the spring so that the pin 51 engages one side or the other of the stop 54 as shown in Figs. 5 and 6, thus providing a positive stopping action at each end of the range of the condenser.

What I claim is:

1. In an electrical tuning condenser having an actuating shaft connected by speed reducing gearing to a condenser tuning shaft, the combination of a cam on the condenser tuning shaft, a stop pin on the actuating shaft, a spring-pressed lever, a cam follower on the lever engaging the cam, and a blocking member on the lever adapted to move into the path of the stop pin under the control of the cam whereby rotation of said actuator shaft is positively and directly arrested upon rotation of said condenser tuning shaft to a given position.

2. In an electrical tuning condenser having an actuating shaft connected by speed reducing gearing to a condenser tuning shaft, a cam on the condenser tuning shaft having an arcuate surface and independently adjustable inwardly inclined surfaces at each end of its arcuate surface, a cam follower resiliently urged against said cam, and means for directly blocking the rotation of the actuating shaft when the cam follower engages either inwardly inclined surface of the cam whereby rotation of said actuator shaft is positively and directly arrested upon rotation of said condenser tuning shaft to either one of two given positions.

3. In an actuating mechanism for a movable-plate type of electrical tuning condenser having an actuator shaft connected by speed reducing gearing to a condenser shaft for the movable-plates, in combination a cam mounted on the condenser shaft in driven relationship thereto, stop means secured to the actuator shaft for rotation therewith, and a cam follower lever engaging the cam and pivotally mounted for cam controlled articulation into the path of said stop means whereby rotation of said actuator shaft is positively and directly arrested upon movement of said condenser shaft to a given position.

4. Actuating mechanism for an electrical tuning condenser wherein a manually operable flexible shaft is connected through an actuator shaft and speed reducing gearing to a movable-plate shaft of the condenser, the latter being movable normally between two limiting positions, comprising in combination therewith a cam mounted on said movable-plate shaft for movement therewith, stop means coupled with said actuator shaft for rotation therewith, and a cam follower lever engaging the cam and pivotally mounted for cam controlled articulation into the path of said stop means, said cam being related to said normal limiting positions of said movable-plate shaft whereby rotation of said actuating shaft is positively and directly arrested before said movable-plate shaft reaches said limiting positions, thereby to preclude driving said movable-plate shaft beyond said limiting positions.

References Cited in the file of this patent a. am 

